Combined effects of global climate change and nutrient enrichment on the physiology of three temperate maerl species

Made up of calcareous coralline algae, maerl beds play a major role as ecosystem engineers in coastal areas throughout the world. They undergo strong anthropogenic pressures, which may threaten their survival. The aim of this study was to gain insight into the future of maerl beds in the context of global and local changes. We examined the effects of rising temperatures (+3ºC) and ocean acidification (-0.3 pH units) according to temperature and pH projections (i.e. the RCP8.5 scenario), and nutrient (N and P) availability on three temperate maerl species (Lithothamnion corallioides, Phymatolithon calcareum, Lithophyllum incrustans) in the laboratory in winter and summer conditions. Physiological rates of primary production, respiration and calcification were measured on all three species in each treatment and season. The physiological response of maerl to global climate change was species-specific and influenced by seawater nutrient concentrations. Future temperature-pH scenario enhance...